During a trust deletion, the backend will fetch all trust by the same
trustor and look for redelegations to be deleted as well. If you have
a considerable amount of trusts that call becomes expensive. Just by
pushing this filter into the backend, the response time for the api call
just depends on the number of redelegations for that trust.
Change-Id: Id3a820fca0bb20561ba031797d2b0fb96ba1f78d
Closes-Bug: #1935840
23477a13ab